Material presser for sewing machines



Dec. 3L, 1940. E. siEFERMANN MATERIAL PRESSER FOR SEWING MACHINES Filed Oct. 4, 1958 Patented Dec. 31, 1940 PATENT OFFICE MATERIAL PRESSER ron SEWING MACHINES Emil Siefermann, Karlsruhe-Durlach, Germany,

assigner to Gritzner-Kayser A.G., Karlsruhe- Durlach, Germany, a corporation of Germany pplication October 4, 1938, Serial No. 233,304.2 In Germany October 5, 1937 4 Claims.

My invention relates to a material presser for sewing machines, more particularly machines for sewing leather.

In leather sewing machines, it is known to pro- 5 vide material pressing devices which lpress upon the workpiece by means of spring action which can be locked in that position and which can be released during the feeding of the workpiece by means of a ratchet wheel drive.

However, the known devices have many disadvantages and it is an object of my invention to provide an improved material presser for sewing machines.

A further object of the invention is to provide a simplied drive for such a presser.

A still further object of the `invention is to provide a drive for a material presser which includes a direct connection between the material presser lever and the operating means therefor. It consists in that with the material presser lever, a rack and pinion wheel is directly connected, which wheel contacts a toothed wheel, the latter being connected with the ratchet'wheel which is pawl driven.

The invention further includes an especially simple construction of the device for lifting the ratchet pawl from the ratchet wheel. It is a rotary disk connectedwith a ratchet wheel and having a swinging lever carrying the ratchet pawl, mounted tangentially to this disk in such manner that said lever at the end of the stroke is pushed out of the locking position by said disk against spring action.

With the foregoing and other objects in view, the invention consists in the details of construction and in the arrangement and combination of parts to be hereinafter more fully set fort and claimed.

In describing the invention in detail, reference will be had to the accompanying drawing forming part of this application, wherein like characters denote corresponding parts in the several views, and in Which- Figure 1 is a section of line I-I of Fig. 2; and

Figure `2 is a plan view.

In the frame I of the leather sewing machine, a material presser 3 is iixedly mounted on a shaft 2. lever 4. The material `presser 3 is pressed into engagement with the workpiece 6 by means of a spring 5. This may be accomplished by the pushing of the upper end of the spring 5 against the shoulder 30 of a member 3i which is pivotally connected, as at 32, with the lever 4 between the free end thereof and the shaft 2. A portion The shaft 2 has fixedly mounted thereon a" 33 of the member 3l engages the upper end of the spring to retain the same in operative engagement. The other end of the spring 5 rests in a tube 34 closed at its lower end 35 and hung up by means of a flange 36 at its upper end in a hole of a bottom wall 3l of the frame I. Obviously, other connections between the spring 5 and lever 4 could be used Without departure from the spirit and scope of the invention. In this position, the lever 4 and presser 3 can be locked by means of any suitable device such as a wedge 49 forming a movable extension of lever 4, which wedge is pressed to the left-by means of a spring 49a. An eccentric disc 49b is mounted on a shaft I3a, which disc rests against the lower surface of the wedge 49, thus supporting it. -Shaft |32* with the eccentric disc 49b is turned and adjusted by a hand wheel 'I which is mounted on the shaft I3. Wedge 49 carries at its left end a roller 49c for a purpose to be described later. In the upper part of the arm 4 there is formed a slot 50 which is partially covered by a plate 5I slidably resting on the arm 4 and connected to the member 49 by screws 52.

In the frame I, a drive crank shaft 9 rotates in bearings 8. This shaft is driven by the handle 42 of a disc flywheel 4I by means of toothed wheels 40. The crank 9 of the shaft 9 drives a rod 43 (shown broken off) which actuates the needle holder with needle (not shown). Furthermore the shaft 9 carries a disk 44 for driving the thread take-up (not shown).

A lever I I is xedly connected to the inner end ofv a pin/V45 which is rotatably mounted in a bearing 46E of the frame. The other en d of the pin 45 rigidly mounts a lever 41. This lever 41 is actuatedlin any suitable manner (not shown) by the handwheel 1 to turn the pin 45 in its bearing 46. The upper end II of the lever II iixedly mounts a plate 48 which is in engagement with the roller 49c of Wedge 49 slidabiy mounted in the lever 4 and forming part of the locking device for the lever 4 and the presser 3. The wedge 49 is subjected to the action of the spring 49a as aforesaid which presses it to the left against the edge of the plate 48 into the locking position. It is obvious from the lforegoing that if by means of the hand wheel I the pin 45 is rotated in a clockwise direction (Fig. 1), the upper end II of the lever II with the plate 48 and the Wedge 49 will be pushed to the right, therebyunlocking the lever 4 and the presser 3. A reverse rotation of the pin 45 again locks the lever 4 and the presser 3.

An arm IIb of the lever II has a roller IIc the shaft 9 rotates.

\ The material presser lever 4 rigidly mounts an angular extension I2 on 'whichv a rack I2, is formed which `contacts a pinion wheel I3'on the shaft I3. vAlso'monnted on shaft I3a is a ratchet wheel yI4fand a circular'disk I5, the latter being of larger diameter-than the 'ratchet wheel. By means of a spring IB, the ratchet wheel I4 and with it the pinion I3 is pulled in a position correspending to the locked position of the material presser 3.

A pawl I1 serves to move the ratchet wheel I4. said pawl being carried by a ratchet pawl lever I8. This lever I8A is swingingly mounted on an arm 'I9a of a mitre lever I9 mounted on the machine frame and Iis actuatedin ,a direction to Y engage pawl I1 withratchet vI4 by atension spring 20, connecting` the free end of lever I8 to another arm I9b of lever I9. .The spring 20 steadily draws pawl I1 in the direction 4of its contact with the ratchet Wheel I4. The mitre lever I9 is actuated by means of a cam diskv2I mounted on the crank shaft 9. One arm-I8b of said lever mounts a roller I9c which is drawn against this disc-like `cam 2I by means of'a spring 22 connected to an additional lever arm IBd. The ratchet pawl lever i8 lies in the same vertical plane as the circular disk I5 and about tangential to it, while the pawl I1 lies in the vertical plane of ratchet wheel' I4.

When the material presser 3 is locked in the pressing position, the cam disks I8 and 2|, together with levers I8 and I9 assume the position indicated in dotted`v lines in Fig. 1. In this position,.the pawl I1 contacts the ratchet wheel I4 at the beginning of the ratchet stroke thereof. After the completion of the sewing stitch, after the needle (not shown), has left'the workpiece 8, the mitre lever I9 is pressed to the right,"as indicated byksolidlines as the rollerV I8c is engaged by the cam 2l which rotates in the direction of the arrow 23. This lowers ratchet pawl lever Il with pawl I 1 and turns the ratchet 'wheel L4 in a counter-clockwise direction. In consequence,

krack I2 is lowered by means of the pinion wheel I3 which depresses arm 4 and lifts the material presser 3. In lits movement to the right and downward, the ratchet pawl lever I8 steadily approaches the circular'disk I5 until it engages the latter. In the succeeding movement, lever I8 is held against further movement to the Kright by'- the circular disk I5, until continued downward 7 gmove'rnent of the -pawl I1 causes it to disengage from -the\teeth'of the ratchet wheel I4. This completes -the stroke of the ratchet wheel. V'I'.he spring 5 again presses the material presser 3 onto the workpiece Ii and thereby turns backtoothed Wheel I3 and the ratchet wheel I4. rlhis turning back movement is aided by spring I8. Y The lever I9 carrying itreturn also during this movement to the starting position, in which the pawl I1 again contacts the ratch wheel I4. Mean- Alimited period during each oscillation of said lever, said pawl engaging sain 'ne direction moves said member out ofengageabove described dirice so it is not my intention to limit myself to the-precise embodiment shown, except as hereinafter claimed.

Having thus described my invention, I claim:

1. In a sewing machineoi the class described, 5 a material presser for releasably holding the work to be sewed in position for sewing@` shaft mounting said presser for arcuate movement into and out of engagement with said work, `an arm ilxed on said shaft, an angular extension of said arm, a. rack formed on said extension, a pinion engagingsaid rack, a shaftv fixedly mounting said pinion, a ratchet wheel xed onsaid shaft, a ratchetwheelspring connected 'to said ratchet wheel and lnormally urging the same vin one direc- 15 tion, a disk xed on said shaft adjacent Asaid' ratchet Wheel, said disk having a slightly greater diameter than said ratchet wheel, said second shaft, pinion and rack comprising means ,for moving said presser into and ont of engagement with the work, a drive shaft, a 'cam xed on the same, a spring loaded lever engaging said cam and oscillated thereby, a pawl carried by said lever, said pawl engaging said ratchet wheel for a 25 lever'to rotate said heel a predetermined dis-z tance against the actionk of said ratchet wheel spring. y 2. In a sewing machine of the class described,

a material presser for releasably holding the work 30 to be sewed in position for sewing, a shaft mounting said presser forl arcuate movement into and out of engagement with said work, an'arm xed on said shaft, an angular extension of said arm, a rack formed on lsaid extension, a pinion engaging said rack, a shaft xedly mounting said pinion, a ratchet wheel iixedvon said shaft, a

ratchet wheel spring connected to said ratchet wheel and normally urging tl'ie same in one direction, a disk fixed on said shaft adjacent said ratchet wheel, said disk having a slightly greater diameter' than said ratchet wheel, `said second shaft, pinion and rack comprising meansfor moving said 'presser into and out of engagement with the work,` a drive shaft, a cam fixedon the same, a spring loaded lever engaging said cam and oscillated thereby, a pawl carried by said ratchet wheel for a limited period `during eachyo'scillationof said lever to rotate said Wheel a predetermined dis- 50 tance against the action of said ratchet wheel I springl a second cam on said drive shaft, a second oscillating lever actuated thereby, and means associated with said second lever for locking said presser in a work holding position.

3, In a sewing machine of the class described; awork engaging member, a ratchet wheel, an

` operative connection between said wheel and said member whereby rotation of said wheel inv menti-fwith said work and vice versa, .a spring loading. said wheel against rotation in a work vdise'ngaging direction, and means periodically'engagingsaid wheel andmcvable to rotate the same in a work, releasing direction, and a camming mechanism continuouslyy driven and operative to periodically release the engagement ofthe wheel engaging whereby` to permit said spring to ratchet pawl lever I8 with pawl I1 andthe mitre rotate said wheel and reengage said work.

4. In a sewingf-r machine Aofthe class described,

engage said work, said last named means including a camming mechanism continuously driven and having operative. connection with the pawl to move the latter into and out of engagement with said ratchet Wheel.

EMIL SIEFERMANN. 

